Process for casting concrete members

ABSTRACT

Concrete members including wall panels and the like are made in a mold having a mold bottom portion formed of a layer of wax cooled to a solid state from a molten state upon the surface of a pool of cold water in a suitable tank. The wax is at least partly supported by the water. Mold side elements having their lower portions embedded in the wax extend upwardly from the wax. Decorative objects such as pieces of stone, tile or the like may be positioned on a reticulated support structure so as to be partly embedded in the solidified wax and thus be partly embedded on a face of the concrete member when the wax is removed. Structural members such as reinforcing elements, door and window frames, electrical boxes and conduits and the like may be embedded in the concrete. Hollow panel members may be produced by making a first slab member with reinforcing elements extending upwardly therefrom, introducing additional water into the tank above the wax and concrete and then forming a second slab member in another similar mold provided by another layer of wax upon the surface of the additional water in conjunction with additional mold side members. When the concrete is partly set hot water is introduced into the tank to melt the wax and accelerate the setting of the concrete. The molten wax is separated from the water for reuse.

United States Patent Scott [22] Filed:

[54] PROCESS FOR CASTING CONCRETE MEMBERS [72] Inventor: Ralph K. Scott, Kennewick, Wash.

[73] Assignee: Columbia Fabricators, Inc., Kennewick, Wash.

July 6, 1970 211 App]. No.: 52,533

[52] US. Cl. ..264/253, 264/37, 264/277, 264/298, 264/317 [51] Int. Cl. ..B28b 1/14 [58] Field of Search ..264/219, 253, 298, 317,

264/DIG. 57; 25/12] Z Primary ExaminerRobert F. White Assistant ExaminerAllen M. Sokal Attorney- -Buckhorn, Blore, Klarquist and Sparkman 1 Sept. 5, 1972 [57] ABSTRACT Concrete members including wall panels and the like are made in a mold having a mold bottom portion formed of a layer of wax cooled to a solid state from a molten state upon the surface of a pool of cold water in a suitable tank. The wax is at least partly supported by the water. Mold side elements having their lower portions embedded in the wax extend upwardly from the wax. Decorative objects such as pieces of stone, tile or the like may be positioned on a reticulated support structure so as to be partly embedded in the solidified wax and thus be partly embedded on a face of the concrete member when the wax is removed. Structural members such as reinforcing elements, door and window frames, electrical boxes and conduits and the like may be embedded in the concrete. Hollow panel members may be produced by making a first slab member with reinforcing elements extending upwardly therefrom, introducing additional water into the tank above the wax and concrete and then forming a second slab member in another similar mold provided by another layer of wax upon the surface of the additional water in conjunction with additional mold side members. When the concrete is partly set hot water is introduced into the tank to melt the wax and accelerate the setting of the concrete. The molten wax is separated from the water for reuse.

22 Claims, 17 Drawing Figures PATENTEDSEP 5 m2 SHEET 1 OF 4 RALPH K. SCOT T INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS PATENTEDsEP 5|972 3.689.626

SHEET 2 [IF 4 V I L g RALPH K. SCOTT INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS minnow 5 m2 3.689.628

SHEET 3 UF 4 ||4 FIG. '0 r RALPH K SCOT T INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS PAIENTEB EP 5 m2 3.689.626

SHEET Q [If 4 FIG. l4 FIG. I5

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WAX SEPARATOR RALPH K. SCOTT INVENTOR I00 86 BY BUCKHORN, BLORE, KLARQUIST 8. SPARKMAN ATTORNEYS PROCESS FOR CASTING CONCRETE MEMBERS BACKGROUND OF INVENTION Concrete members have been produced by employing a mold having a mold bottom portion formed of a layer of wax cooled to a solid state from a molten state upon the upper surface of a solid support member made of metal, wood or the like. Decorative articles such as pieces of stone have been positioned upon the upper surface of the solid support member so as to be partly embedded in the solidified wax. These articles are partly embedded in a face of the resulting concrete member and are exposed when the wax is removed.

One proposal to facilitate removal of the wax has been to lightly spray the interior of the mold including any decorative articles therein with water prior to introducing molten wax into the mold in order to prevent adherence of the wax to the mold. After the concrete has set, the mold is removed and the wax dislodged from the concrete member by striking the wax with a mallet. It is difficult to remove all of the wax in this manner and also upon cooling the wax tends to irregularly pull away from the moistened decorative articles so that the concrete mix poured into the mold penetrates into contact with and adheres to outer portions of the rocks or other decorative articles so as to impair the desired decorative effect.

In my copending application Ser. No. 805,178 filed Mar. 7, 1969 now US. Pat. No. 3,608,051, a method of removing the wax is disclosed in which hot water is circulated around the mold members and into direct contact with exposed peripheral edges of the wax layer to melt the wax. This is an improvement over the prior proposal in that the wax is completely removed and can be easily separated from the hot water for reuse. The improved method also avoids the difficulty of penetration of the concrete mix around the decorative articles resulting from the wetting of such articles prior to introducing the wax.

SUMMARY In accordance with the present invention, a process and apparatus is provided by which a layer of wax or similar fusible material forming the bottom portion of a mold is at least partly supported upon the surface of a pool of cold liquid in a suitable tank during the casting of the concrete. The preferred fusible material is a petroleum wax and the preferred liquid is water and the invention will be described with reference to such wax and water.

The use of cold water to at least partly support the wax enables this water to be displaced rapidly by hot water after the concrete has set and the hot water can then be circulated in contact with the entire lower surface of the layer of wax. Rapid melting and recovery of the wax is thus accomplished.

A reticulated support structure such as a metal grating or metal screen, for example, hardware cloth, or a combination of both can be employed to support decorative articles in desired positions prior to introducing the molten wax. A mold structure made of mold side elements and having an open bottom and tops is positioned in the tank and supported upon the reticulated support structure or otherwise supported. The level of the water, upon which the layer of wax is formed, is maintained below the upper surface of such reticulated support structure and preferably below the lower edges of the mold side members. This water is thus maintained out of contact with any decorative articles and the mold side elements.

Molten wax is introduced into the tank from a wax supply tank so as to cover the water the reticulated support structure and also cover the lower edges of the mold side elements. The water can be sufficiently cool so that a surface skin of wax immediately solidifies in contact with the water to support a superimposed layer of molten wax. The molten wax flows to produce a level upper surface. Cold water can then be circulated below the wax to rapidly cool and solidify the wax. The resulting layer of solid wax is at least partly supported on the reticulated support structure and locks the mold side elements in place with respect to each other and to the support structure. A concrete mix is then introduced into the mold, vibrated to settle the concrete mix and remove voids and can be screeded to provide a smooth top surface if desired.

The wax shrinks during cooling and for large panels, it may be necessary prior to cooling the wax to cross brace the mold side elements above the surface of the wax against inward bowing, or it may be necessary to cut the wax layer from the interior side of such side elements with a sharp instrument when the wax has partly solidified in order to prevent such bowing and also in some cases to prevent tension cracking of the wax.

The shrinking properties of the wax may, however, be employed to provide interesting and decorative surfacepattems on the face of a concrete member cast against the surface of the wax. These patterns result from shrinkage of the wax between the support points or lines provided by the reticulated support structure below the wax and can be varied by varying the nature of this support structure and by varying the thickness of the portion of the wax layer above such support structure.

A reinforcing structure such as a mesh of reinforcing iron can be positioned in the concrete mold either before or after pouring a concrete mix into the mold.

Hollow panel members having concrete slab members spaced from each other and joined together by metal reinforcing elements can also be produced extending between adjacent faces of the slab members. For example, a lower first slab member may be poured as described above and while the concrete mix is still fluid, a reinforcing structure made of metal mesh elements held in spaced relationship by metal reinforcing elements extending between the mesh elements may be positioned to immerse the one of the mesh elements in the poured concrete mix and leave the upper mesh element supported above and spaced from the concrete mix. An upper-mold structure having side mold elements and an open top and bottom is also positioned in the tank so as to surround the upper mesh element either before or after the reinforcing structure is installed.

Additional water is added to the tank after the reinforcing structure is in place to bring the water to a level just below the side elements of the upper mold structure. Additional molten wax is then introduced into the tank to cover the surface of the water and the lower edges of the upper side elements in the same manner above described including circulation of cold water below-the upper wax layer thus formed to cool and solidify the wax. A solid wax layer partly supported by the reinforcing elements extending upwardly from the concrete mix in the lower mold is thus formed as the upper mold bottom element. Further concrete mix is then poured into the resulting upper mold and can be vibrated and screeded as above described to form an upper slab spaced from the lower slab.

When the concrete of the resulting concrete member, which may be either a solid member or a hollow member, has sufficiently set to be self sustaining, the cold water in the tank can be displaced by hot water and hot water circulated through the tank until all of the wax is melted and removed. The resulting concrete member may then be removed and the molding apparatus above described reused to make another article. Elements for connecting hoisting cables can be cast into the concrete members, if desired, as can aiso any desired structural members such as door frames, window frames and electrical conduits and outlet boxes.

It is therefor an object of the invention to provide an improved process and apparatus for making concrete members by which concrete panels or the like having decorative surfaces including hollow wall structures may be rapidly produced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view with portions broken away to show interior structure of a preferred embodiment of a tank suitable for making concrete members in accordance with the invention;

FIG. 2 is a partial vertical section on an enlarged scale taken on the line 2-2 of FIG. 1 with the top of the tank omitted;

FIG. 3 is a partial vertical section on the same scale as FIG. 2 of another portion of the tank and taken on line 33 of FIG. 1;

FIG. 4 is a vertical section similar to FIG. 3, taken on the line 4-4 of FIG. 1;

FIG. 5 is a plan view of a floating skimmer structure forming part of the tank of FIG. 1;

FIG. 6 is a partial vertical section on a further enlarged scale of a part of the structure shown in FIG. 4, showing additional structure;

FIG. 7 is a fragmentary plan view of a water distribution trough shown in FIG. 7;

FIG. 8 is a fragmentary vertical section on the same scale as FIG. 6, showing a poured concrete member and a solidified wax layer partly supported on the surface of a pool of water in a tank and partly supported by a grating;

FIG. 9 is a fragmentary plan view of the top surface of the concrete member cast on the solidified wax layer of FIG. 8;

FIG. 10 is a fragmentary vertical section on a still further enlarged scale, showing a thicker layer of wax than in FIG. 9, also partly supported by a mesh;

FIG. 11 is a view similar to FIG. 10 showing ornamental objects also supported on the mesh;

FIG. 12 is a fragmentary plan view of the surface of the concrete member of FIG. 1 1;

FIG. 13 is a partial vertical section showing apparatus for casting a hollow wall panel;

' FIG. 14 is a side elevation of a typical reinforcing element employed in making the hollow wall panel of FIG.

FIG. 15 is a vertical section taken on the line 1515 of FIG. 14;

FIG. 16 is a fragmentary vertical section of a hollow wall member made in the apparatus of FIG. 13; and

FIG. 17 is a schematic diagram of a suitable system for supplying water and molten wax to the tank of FIG. 1 and circulating cold and heated water through the tank as well as separating wax from the heated water.

DESCRIPTION OF A PREFERRED EMBODIMENT A suitable tank 20 for making large scale panels such as wall panels for a house of other building is shown in plan view in FIG. 1, with portions progressively broken away to show interior structure. As shown most clearly in FIGS. 2, 3 and 4, the tank includes a floor structure 22 made up, for example, of hollow sections having upper and lower plywood sheets 24 secured together by spaced joists 26 with the space between the joists filled with heat insulating material 28. As indicated by thedotted lines 30 in FIG. 1, the floor structure 22 of the tank 20 may be made in sections, for example of the size of standard 4x8 plywood sheets. These sections may be temporarily joined together for use of the tank in one location and then separated if it is desired to move the tank to another location where a building is being constructed.

The tank 20 has side walls 32 and end walls .34 of similar construction, also made up of plywood sheets 36, and top and bottom framing members 38 with the hollow portions of the side walls also filled with heat insulating materials 40. It will be understood that the side walls and end walls will also have suitable vertically extending studs not shown.

The side and end walls may be removably supported on the floor structure 22 and held in upright position by metal posts 42 made of metal pipe extending through holes in the top and bottom framing members 38 of the side and end walls and also extending downwardly through holes in suitable bracing members 44 in the edges of the floor structure 22. The floor structure 22 is supported in level position upon suitable beams 46, except for a well portion 48 in one comer of the floor structure 22 in which a portion 50 of the floor structure is depressed below the general level of the floor structure 22. As described in more detail below, the well portion 48 provides a sump for collection of liquid from the rest of the tank so as to enable the liquid to be more readily pumped from the tank. T0 render the tank liquid tight, a sheet 52 of heavy flexible plastic material, such as a thick sheet of polyvinyl chloride is employed to cover the entire interior of the tank 20 including the interior surfaces of the well 48 and the side and end walls 32 and 34 of the tank, the sheet extending over the top of such walls. A plywood cap member 54 is positioned on the top of all of these walls to cover and protect the edge portions of the plastic sheet 52.

A plurality of spacer strips 56 are laid on top of the plastic sheet 52 so as to extend longitudinally of the tank. These spacer strips are spaced laterally from each other and may, for example, be made of narrow strips of wooden material. These spacer strips extend over the major portion of the floor area of the tank but terminate short of the well area 48 and of the end walls 34 of the tank. A reticulated support structure 58 which may, for example, include a standard form of floor grating constructed of iron or steel strips approximately As indicated in FIG. 6, a distribution trough 60 may extend across the end of the tank remote from the well 48. The trough has side elements 62 spaced upwardly from the plastic sheet 52 forming the bottom of the tank by spacer elements 64 spaced along the trough so that water can flow laterally of the trough below the side elements. Cold water may be introduced into the distribution trough 60 through a flexible conduit 66 to fill the tank up to a level indicated by the dotted line 68. A flexible conduit 70 is also shown in FIG. 6 through which melted wax may be introduced into the tank 20 on top of the water so that the melted wax reaches a level indicated by the dotted line 72 in FIG. 6. A layer of molten wax 73 is formed between the dotted lines 68 and 72 of FIG. 6 covering the entire floor area of the tank on top of the pool of water in the tank, the water distribution trough 60 being provided primarily for allowing cold water to be subsequently circulated below the wax layer 73 to solidify the wax into a solid layer. It will be apparent that, in general, the upper surfaces of the strips or elements of the reticulated support structure for the wax should all be as nearly at a common level as is practicable.

Mold side elements 74 are also installed in the tank and as indicated in FIG. 6, the mold side elements may rest on the top of the grating 58 and be held in position in the tank by bracing elements 76 and 78 bearing against the walls of the tank, for example, the end wall 34 shown in FIG. 6.

As described in more detail below, the panel making operation includes circulation of cold water below the wax layer 73 for cooling the wax to solid form and also subsequently flooding the tank with hot water and circulating such water below the grating 58 to melt solidified wax forming part of the mold structure. This hot water also accelerates setting of the concrete of the concrete member. The tank 20 is also provided with a heat insulating top 80 shown in FIGS. 1, 3 and 4. This top is removable and may be conveniently made of members 82 of polystyrene foam or other solid plastic foam material which may be several inches thick. These plastic foam members may be, for example, 4 feet wide and be attached to supporting members 84 extending lengthwise across the tops of the sheets and supporting such sheets. Extending ends of the supporting member 84, which, may, for example, be made of 2x4 wooden strips, provide handles for removal and reinstallation of the sections of the top 80.

As shown in FIGS. 1, 2 and 5, a floating skimming structure 86 is removably positioned in the well 48. This skimming structure may include a rectangular metal frame 88 made up of angle iron welded together. Hollow metal float members 90 are positioned below each comer of the frame 88 and secured to the frame to buoyantly support the skimming structure 86 on any liquid in the tank 20. A cup-shaped skimming element 92 having an open top is supported below and centrally of the frame 88 in a central space between the floats 90. This skimming element is adjustably supported on the frame 88 by vertically extending threaded elements 94 so that the upper edge of the skimming element 92 may be positioned just below the liquid level in the tank, it being understood that the skimming structure 86 will float up and down on such liquid. The purpose of the skimming structure is to rapidly remove an upper layer of molten wax which forms on the pool of hot water to facilitate separation of such molten wax from the hot water for reuse of the wax.

In general, the skimming structure 86 is lifted from the tank during the time that the molten wax is being introduced into the tank and solidified on top of a water layer therein. Subsequently the cover is positioned on the top of the tank 20 and the tank flooded with hot water to melt the wax. After the wax has been melted by the hot water, the skimming structure 86 is employed to remove molten wax and heated water from thetank. The wax and heated water is removed from the skimming element 92 through a flexible conduit 96 extending into the skimming element and secured to the frame 88 of the skimming structure, this conduit being provided with a foot valve 97 for preventing reverse flow of liquid. Another flexible conduit 98 having a foot valve 100 is also provided for removing residual water from the lower portion of the well 48 below the lowest level reached by the upper rim of the skimming element 92 and for removing cold water from the tank 20. This additional conduit 98 may also be employed as part of the cold water circulating system when a layer of molten wax is being solidified in the tank.

In making a wall panel in accordance with the present invention, a pool of cold water is established in the tank up to the desired level 68 of FIG. 6 by introducing cold water through the conduit 66 of FIG. 6. After the pool of cold water has been established in the tank, molten wax is introduced into the tank through the conduit 70 and distributed over the surface of the water therein. This wax is distributed not only within the confines of the mold provided by the mold side elements 74 but also over the entire surface of the water in the tank except for the interior of the water distribution trough 60 and during the cooling of the wax, the conduit 96 and foot valve .100 may also be left in position. A relatively thin layer of the wax immediately solidifies on contacting the cold water in the tank and continued application of molten wax forms a pool of molten wax throughout the area of the tank having a substantially level upper surface. As indicated in FIG. 6, the upper level of the wax is above the lower edge of the mold side elements 74 while the lower level of the molten wax is below the edge of the mold side elements. The molten wax will thus flow laterally of the tank between the strips of the grating 58 and outside of the interior of the mold along the side edges of the mold and then around the ends of the mold adjacent the ends of the tank 20. As soon as a desired upper level 72 of the pool of molten wax has been obtained and the wax has been partly solidified, cold water circulation under the layer of wax may be produced by introducing cold water through the conduit 66 and withdrawing it through the conduit 98 to cause the wax to completely solidify. When the wax layer has been cooled to form a solid wax layer such as the layer 102 of FIG. 8, a charge of concrete mix can be poured into the mold having its bottom wall provided by the wax layer 102. The concrete mix is usually vibrated to settle it and is screeded to level.

FIG. 8 illustrates what happens to the upper surface 104 of the wax layer upon cooling of the wax, if the solidified wax layer 102 above the strips of the grating 58 is relatively thin. This surface of the wax layer assumes a rippled or corrugated conformation due to the shrinkage of the wax between the grating strips. The lower face of the concrete member 106 in contact with the wax layer 102 conforms to the upper surface 104 of the wax layer to provide a grooved or rippled face 107, such as shown in FIG. 9.

The floor gratings 58 are manufactured with suffi- I cient accuracy, that the individual grating strips of adjacent sections of the grating positioned upon the spacer strips 56 on the floor of the tank are easily aligned so that the ripples extend entirely across a panel and produce a pleasing pattern. By employing gratings 58 of different desings, for example, gratings having'strips positioned at angles to each other or curved to form ornamental designs, many different patterns can be produced in low relief upon the surfaces of the panel of the concrete member case in contact with the wax.

It is possible also to produce various patterns by superimposing a mesh, such as a woven mesh, upon the strips of the grating 58. If the mesh or screen has openings of substantial size and the layer of wax above the mesh is relatively thin, a mesh pattern having ridges running at right angles to each other will be produced. As the meshes are made smaller, the pattern becomes less distinct and also the distinctness of the pattern becomes-less as the layer of the wax above the mesh is increased. This is illustrated in FIG. in which the upper surface of a wax layer 108 is completely smooth. A screen or mesh indicated at 110 is incorporated in the wax layer by supporting such mesh upon the strips of the grating 58. The smooth upper surface of the wax layer produces a very smooth lower surface 112 on a concrete member 114 cast in contact with the upper surface of such wax layer.

The embedding of decorative articles, such as flattened stones 116, in the surface of the concrete member 118 is illustrated in FIG. 11. In this figure a screen or mesh 120 is shown supported by the strips of the grating 58 and the stones 116 are laid upon such mesh 120. A layer of wax produced by introducing molten wax into the mold upon the upper surface 68 of a pool of water and cooling the wax has sufficient thickness to partially embed the stones 116. Thus the cooled wax reaches'the level 122 and upon cooling produces the solid wax layer 123. When the wax is removed from the lower face of the concrete member 118 in FIG. 11, the stones are left partly embedded in the concrete of such member to provide a decorative surface. Such decoration is of course not limited to stones but may be tiles or plaques, or pieces of glass, etc. They may be arranged to substantially cover the surface of the concrete member or may be arranged in geometrical or other decorative figures. By way of example, the surface of a concrete member covered with spaced decorative stones 116 is shown in FIG. 12. In general, all of the concrete members, if they are of substantial size, will have reinforcing iron cast therein and the concrete members 106, 114 and 118 of FIGS. 8, 10 and 1 1 are each shown as having a centrally reinforcing mesh 124.

FIG. 13 illustrates how a hollow wall member having spaced slab elements 126 and 128 shown in FIG. 16 can be produced. The lower panel slab element 126 can be made in the same manner as the concrete members 106, 114 or 118 discussed with respect to FIGS. 6, 10 and 11, respectively. The only difference is that the reinforcing mesh 124 is part of a reinforcing structure 129 also including a similar upper reinforcing mesh 130, the two reinforcing meshes 124 and 130 being held in spaced relationship with respect to each other by reinforcing members 132 extending between the two meshes and secured thereto. For example, the reinforcing members 132 extending between the two meshes 124 and 130 may be standard reinforcing members of the type shown in FIG. 15 having spaced bars 134 connected together by a sinuously extending bar 136 welded to the bars 134 at spaced points along these bars. A plurality of reinforcing members 132 may be wired to the meshes 124 and 130 to form triangular bracing portions when viewed in cross section as in FIGS. 13 and 16, looking lengthwise of the reinforcing members 132.

Immediately after the concrete mix for the lower slab element 126 has been poured and while this mix is still fluid, a prefabricated reinforcing structure 129 of the type just described may be moved into position and one of the reinforcing meshes 124 pressed downwardly into the concrete mix for the lower slab 126. Additional cold water is then introduced into the tank 20 through the conduit 66 of FIG. 13 to raise the water level in the tank to that indicated by the dotted line 138 in FIG. 13. Additional molten wax is then introduced through the conduit in the same manner as described above with respect to FIG. 6. Cold water can then be circulated below the partly solidified wax layer until the wax solidifies into a solid layer 140 above the water level 138. The reinforcing bars 136 of the reinforcing members 132 extend upwardly through the cooled wax layer 140 and hold the upper mesh member above such wax layer.

Additional mold side members 142 can be installed and held in position by support members 144 and bracing members 146 and 147 so that another concrete mix can be poured into the mold provided by the solid wax layer and the mold side elements 142. For convenience in handling a hollow wall member after it is formed, metal or plastic tube members 148 can also be positioned with their lower ends in the concrete mix for a lower slab element 126 prior to setting of the concrete of such slab element so as to extend upwardly through the wax layer 140 into the mold provided above such wax layer. The tubular members 148 are installed before introducing the molten wax to form the wax layer 140 of FIG. 13. A second water distributing trough 150 may also be supported in the tank 20 prior to pouring in the molten wax for the second wax layer 140 for convenience in circulating water through the tank below the wax layer 140.

After the concrete mix for the upper slab element 128 has been set, sufficient to be self-sustaining, the wax can be melted and removed from the tank as described in more detail below, and the hollow wall member removed from the tank of FIG. 13.

A schematic diagram of a water and wax system for the tank 20 is shown in FIG. 17. Except for the tank 20 all of the elements of such a system can be mounted in and carried by a single trailer of an over the highway tractor trailer combination for transport from one job location to another and, as stated above, the tank 20 can be disassembled for transport. This system includes a hot water tank 152, which may, for example, hold 1800 gallons, a cold water tank 154 of a similar size and a wax separator tank 156, which may, for example, hold 2200 gallons, the hot water tank 152 preferably being at a higher elevation than the wax separator tank 156. The system also includes a heat exchanger 158, a pair of circulating pumps 160 and 162, and a tank pump 164, the conduits 66,70, 96 and 98 referred to above, being also shown in FIG. 17. An additional wash down conduit 166, not shown in the other figures, is also shown in FIG. 17.

In carrying out a process for producing a concrete member such as a concrete wall panel, the tank 20 is first filled with cold water up to the water level 68 indicated by thedotted line in FIG. 6 through the conduit 66. Thus water from the cold water tank 154 may be delivered by gravity through the conduit 168 and valves 170 and 172. The valve 170 is of the type which can be changed from a cold water position in which cold water is delivered through a conduit 174 and the valve 170 to the valve 172 in the conduit 60, or to a hot water position in which hot water is delivered through the conduit 168 and the valve 170 to the valve 172. By cold water is meant water have a temperature approximating ambient temperature unless the ambient temperature is extremely low in which the cold water may be tempered with hot water from the conduit 174 to raise the temperatureof such water to approximately 50 to 80 F., or the tank can be preheated by circulation of water therethrough.

When the desired water level 68 has been established, the valve 172 is closed and melted wax from the wax separator tank 156 is delivered into the tank 20 through the conduit 70 through the valve 175. The wax is maintained in a molten condition in the wax separator tank 156 by circulation of hot water through this tank. This water is maintained at a temperature substantially above the melting point of the wax by circulation through the heat exchanger 158. This circulation is accomplished by withdrawing water from the hot water tank 152 through the conduit 176 and valve 178 by the pump 160 and discharging this water from the pump 160 through the valve 180 and the conduit 182 through a check valve 184 back into the tank 156. The water flows through the tank 156 below any wax present in this tank and flows through the heat exchanger 158 back into the hot water tank 152 through a valve 186. After this circulation of water through the heat exchanger 158 has brought the wax in the tank 156 to a molten condition, the valve 186 may be closed and the valve 175 opened. Since the heated water can no longer escape from the tank 156 through the valve 186, pumping water into the tank 156 from the hot water tank 152, forces the wax out of the tank through the valve 175 and conduit to introduce wax into the tank 20. When sufficient wax has been introduced into the tank 20 to reach the desired level such as the level 72 of FIG. 6, the valve 186 is opened and the valve 175 closed to re-establish the circulation of hot water through the tank 156 and heat exchanger 185. The pump 160 can then be shut down, if further heating of the wax or the water in the tank 152 or 156 is not required.

As stated above, a thin film of solid wax almost immediately forms on the surface of the water with a pool of molten wax above this film. In order to more rapidly cool the wax, cold water is then circulated below the resultant layer of wax, i.e. by introducing cold water through the conduit 66 and withdrawing it through the conduit 98. Before starting the cold water recirculation through the tank 20, it is desirable to completely refill the cold water tank 154 through the valve 188 and close any air intake valve into such tank. By so doing the cold water system can be made a completely filled closed system so that water will flow out of the tank 154 at the same rate it is pumped into the tank during circulation of the cold water.

The cold water circulation is accomplished by employing the tank pump 164 to withdraw water from the tank 20 through the conduit 96. The water is forced by the pump 164 through valve 190 and valve 192 into the cold water tank 154. The valve 192 is of the type in which one position of the valve connects the pump 164 through the valve 190 to the cold water tank 154 and the other position of the valve connects the pump 164 through the valve 190 and the conduit 182 to the wax separator tank, as described below. The valve is actuated to connect the conduit 168 with the conduit 66 through the valve 172 so that cold water from the tank 154 is delivered back into the tank 20 through the conduit 66.

The tank 154 will ordinarily be positioned a few feet only above the tank 20 so that no vacuum above the water in the tank 154 is produced. Water is thus delivered back into the tank 20 by the circulating system just described at the same rate as it is withdrawn therefrom by the pump 164. It is to be noted that the hot water circulation described above employing the pump 160 to force water through the valve and conduit 182 and then through the wax separator tank 156 and hot water tank 152 can be carried out during the cold water circulation just described through the tank 20, thus enabling the wax to be kept hot in the wax separator tank 156 during cold water circulation through the tank 20.

After the wax layer has solidified, a concrete mix can be poured into the mold provided by the mold side elements 74 shown in FIG. 6, the solidified wax layer 73 forming the bottom of the mold. This wax layer extends around the outer perimeter of the mold side elements 74 as well as around the inside of such elements and that the lower edges of the mold side elements 74 are embedded in the wax layer so that the mold side elements are held rigidly in position by the wax.

If a single layer concrete member is to be made, the concrete mix in the mold is allowed to set sufiiciently to be self sustaining and thereafter hot water is introduced into the tank 20 through the conduit 66. The hot water is pumped from the tank 152 by the pump 160 through the conduit 176, and valve 178 and is discharged from the pump 160 through valve 180, conduit 182 and delivered through the wax separator tank 156, heat exchanger 158, conduit 174, valves 170 and 172 and conduit 66 into the tank 20. There is no necessity for maintaining a constant level of hot water in the tank 20. The purpose of the hot water is to melt the layer of wax in the tank and also assist in rapidly finishing the curing of the concrete member in the tank 20. In order to retain as much heat as possible in the tank during this heating operation, the covers 80 of FIGS. 1, 3 and 4 are installed on the tank. Circulation of hot water through the tank 20 can be started by employing the pump 164 to withdraw hot water and wax through the conduit 96 and deliver it through the valve 190, valve 192, conduit 182 and check valve 184 into the wax separator tank 156.

When the wax is substantially melted, the skimmer structure 86 and conduit 96 can be substituted for the conduit 98 by closing a valve 194 in the conduit 96 and opening a valve 196 in the conduit 98. It will be apparent from FIG. 2 that liquid wax will first flow into the skimmer cup 92 and be pumped into the tank 156. Such wax separates from the hot water in the tank 156 and the hot water being pumped into the tank 156 can be discharged from this tank through the heat exchanger 158, the conduit 174, valve 170 and valve 172 back into the tank 20.

The conduit 166 can be employed at any time to wash down the tank and remove any adhering wax from any concrete member in the tank by pumping hot water from the water tank 152 through the valve 178 by the pump 160 and then through the pump 162, valves 198 and 200 into the tank 20 through the conduit 166. The two pumps 160 and 162 in series provide water under substantial pressure to produce a high velocity stream for washing purposes. It is to be noted that the skimming operation above described can be continued by keeping the pump 164 in operation. After the wash down operation by the conduit 166 is completed, the pump 164 can be employed to remove most of the hot water from the tank 20 through the skimmer structure 92 and deliver it into the hot water tank 152 through the wax separator tank 156. Residual hot water can be removed from the tank through the conduit 96 and valve 196 by pump 164 and also delivered in the same manner into the hot water tank 152.

If it is desired to make a hollow wall panel structure involving a second slab 128 spaced from a lower slab as shown in FIG. 14, instead of introducing hot water into the tank to melt the wax after the lower slab has been produced, a reinforcing structure 129 having two spaced meshes 124 and 130 is first installed and then additional cold water is introduced into the tank from the cold water tank 154 through the conduit 168, valve 170, valve 172 and conduit 166 as above described. Molten wax is then introduced through the conduit 70 as above described. The procedure in making the second slab member 128 shown in FIG. 16 is entirely similar to that just described below with respect to making a first concrete slab member 126. After the upper or second slab has been cast and partly set, the top 80 is installed on the tank and hot water introduced to melt the wax and finish the curing of the concrete.

The wax and hot water are separated as above described and residual hot water removed from the tank to ready the tank for another casting operation. It should be noted that the final curing of the concrete under heat provides a desirable white color for the concrete panels. 7

The wax employed is preferably a petroleum wax having a melting point of approximately F. and the liquid for partly supporting the wax is preferably water. It will be apparent, however, that it is the physical properties of these materials which is of importance and that other liquids and other fusible materials having suitable physical properties can be employed, so long as the fusible material is of less density than the liquid and immissible with the liquid so that it floats on the liquid and the fusible material has a melting point somewhat above usual ambient temperatures and at a temperature at which the liquid remains in a liquid condition.

I claim: 1. The process of forming a concrete member which comprises:

forming a layer of solidified fusible material from molten fusible material upon the surface of a pool of liquid of greater density than said fusible material and at a temperature below the melting point of the fusible material to provide a mold bottom element in a mold structure having mold side elements;

casting a concrete member in said mold structure by introducing a concrete mix into said mold structure and into contact with said mold bottom element and allowing said concrete mix to set;

and melting said fusible material to separate said fusible material from said concrete member by circulating liquid at a temperature above the melting point of said fusible material in contact with the lower surface of said mold bottom element.

2. The process of claim 1 in which the concrete mix is introduced into said mold structure and allowed to set while said solidified fusible material is at least partly supported by said liquid.

3. The process of claim 2 in which said solidified fusible material is also partly supported by a supporting structure having spaced elements for providing contact between the lower surface of said mold bottom element and said liquid.

4. The process of claim 1 which includes positioning said mold side elements to have their lower edges embedded in said layer of fusible material.

5. The process of claim 1 in which a reinforcing structure having a spaced upper and lower horizontally extending reinforcing elements and vertically extending reinforcing elements connected between horizontally extending reinforcing elements is positioned with said lower horizontally extending reinforcing elements immersed in said concrete mix and with said upper horizontally extending reinforcing elements supported above and spaced from said mold structure and within a similar upper mold structure;

and additional liquid at a temperature below the melting point of said fusible material is introduced into said tank to raise the liquid to a level below and adjacent said upper mold structure;

and forming an upper layer of solidified fusible material upon the surface of said additional liquid to provide a mold bottom element for said upper mold;

casting a second concrete member in said second mold and allowing it to set;

and thereafter employing said heated liquid to melt said fusible material. 6. The process of claim 1 in which the fusible material in molten form is distributed upon the surface of said pool while the liquid of said pool is at a temperature causing a film of solid fusible material to form on said liquid;

additional molten fusible material is thereafter distributed upon said thin layer to form a layer of molten fusible material superimposed on said film;

and additional liquid is circulated below said layer to remove heat from said fusible material to solidify said fusible material into a solid layer.

7. The process of claim 1 in which said solidified fusible material is a wax and is partly supported by a reticulated supporting structure.

8. The process of claim 7 in which a layer of said fusible material is cooled to solid form while in contact with said reticulated supporting structure and while said reticulated supporting structure is at least partly embedded in said fusible material with a portion of said layer extending above said reticulated supporting structure.

9. The process of claim 7 in which the melted fusible material is solidified when said portion of said layer is sufficiently thin to provide a pattern on the upper surface of said layer similar to the solid elements of said reticulated supporting structure to thereby provide a decorative pattern on a concrete member cast in contact with the said upper surface of said layer.

10. The process of claim 8 in which sufficient melted fusible material is added to cause said upper surface of said layer to have a substantially smooth upper surface.

11. The process of claim 8 in which a decorative insert is supported on said reticulated supporting structure and said layer of fusible material and is partly submerged in said layer of fusible material.

12. The process of forming a concrete member which comprises:

forming a layer of solidified fusible material from molten fusible material upon the surface of a pool of liquid of greater density than said fusible material and at a temperature below the melting point of the fusible material to provide a mold bottom element in a mold structure having mold side elements;

castinga concrete member in said mold structure by introducing a concrete mix into said mold structure and into contact with said mold bottom element and allowing said concrete mix to set;

and heating said fusible material to a temperature above the the melting point of said fusible material to melt said fusible material and separating the melted fusible material from said concrete member.

13. The process of claim 12 in which the concrete mix is introduced into said mold structure and allowed to set while said solidified fusible material is at least partly supported by said liquid.

14. The process of claim 13 in which said solidified fusible material is also partly supported by a supporting structure having spaced elements for providing contact between the lower surface of said mold bottom element and said liquid.

15. The process of claim 12 which includes positioning said mold side elements to have their lower edges embedded in said layer of fusible material.

16. The process of claim 12 in which a reinforcing structure having a spaced upper and lower horizontally extending reinforcing elements and vertically extending reinforcing elements connected between horizontally extending reinforcing elements is positioned with said lower horizontally extending reinforcing elements immersed in said concrete mix and with said upper horizontally extending reinforcing elements supported above and spaced from said mold structure and within a similar upper mold structure;

and additional liquid at a temperature below the melting point of said fusible material is introduced into said tank to raise the liquid to a level below and adjacent said upper mold structure;

and forming an upper layer of solidified fusible material upon the surface of said additional liquid to provide a mold bottom element for said upper mold;

casting a second concrete member in said second mold and allowing it to set;

and thereafter employing said heated liquid to melt said fusible material. 17. The process of claim 12 in which the fusible material in molten form is distributed upon the surface of said pool while the liquid of said pool is at a temperature causing a film of solid fusible material to form on said liquid;

additional molten fusible material is thereafter distributed upon said thin layer to form a layer of molten fusible material superimposed on said film;

and additional liquid is circulated below said layer to remove heat from said fusible material to solidify said fusible material into a solid layer.

18. The process of claim 12 in which said solidified fusible material is a wax and is partly supported by a reticulated supporting structure.

19. The process of claim 18 in which a layer of said fusible material is cooled to solid form while in contact with said reticulated supporting structure and while said reticulated supporting structure is at least partly embedded in said fusible material with a portion of said layer extending above said reticulated supporting structure.

20. The process of claim 18 in which the melted fusible material is solidified when said portion of said layer is sufficiently thin to provide a pattern of ridges on the upper surface of said layer similar to the solid elements of said reticulated supporting structure to thereby provide a decorative pattern on a concrete member cast in contact with the said upper surface of said layer.

21. The process of claim 19 in which sufficient melted fusible material is added to cause said supper surface of said layer to have a substantially smooth upper surface.

22. The process of claim 19 in which a decorative insert is supported on said reticulated supporting structure and said layer of fusible material and is partly submerged in said layer of fusible material. 

2. The process of claim 1 in which the concrete mix is introduced into said mold structure and allowed to set while said solidified fusible material is at least partly supported by said liquid.
 3. The process of claim 2 in which said solidified fusible material is also partly supported by a supporting structure having spaced elements for providing contact between the lower surface of said mold bottom element and said liquid.
 4. The process of claim 1 which includes positioning said mold side elements to have their lower edges embedded in said layer of fusible material.
 5. The process of claim 1 in which a reinforcing structure having a spaced upper and lower horizontally extending reinforcing elements and vertically extending reinforcing elements connected between horizontally extending reinforcing elements is positioned with said lower horizontally extending reinforcing elements immersed in said concrete mix and with said upper horizontally extending reinforcing elements supported above and spaced from said mold structure and within a similar upper mold structure; and additional liquid at a temperature below the melting point of said fusible material is introduced into said tank to raise the liquid to a level below and adjacent said upper mold structure; and forming an upper layer of solidified fusible material upon the surface of said additional liquid to provide a mold bottom element for said upper mold; casting a second concrete member in said second mold and allowing it to set; and thereafter employing said heated liquid to melt said fusible material.
 6. The process of claim 1 in which the fusible material in molten form is distributed upon the surface of said pool while the liquid of said pool is at a temperature causing a film of solid fusible material to form on said liquid; additional molten fusible material is thereafter distributed upon said thin layer to form a layer of molten fusible material superimposed on said film; and additional liquid is circulated below said layer to remove heat from said fusible material to solidify said fusible material into a solid layer.
 7. The process of claim 1 in which said solidified fusible material is a wax and is partly supported by a reticulated supporting structure.
 8. The process of claim 7 in which a layer of said fusible material is cooled to solid form while in contact with said reticulated supporting structure and while said reticulated supporting structure is at least partly embedded in said fusible material with a portion of said layer extending above said reticulated supporting structure.
 9. The process of claim 7 in which the melted fusible material is solidified when said portion of said layer is sufficiently thin to provide a pattern on the upper surface of said layer similar to the solid elements of said reticulated supporting structure to thereby provide a decorative pattern on a concrete member cast in contact with the said upper surface of said layer.
 10. The process of claim 8 in which sufficient melted fusible material is added to cause said upper surface of said layer to have a substantially smooth upper surface.
 11. The process of claim 8 in which a decorative insert is supported on said reticulated supporting structure and said layer of fusible material and is partly submerged in said layer of fusible material.
 12. The process of forming a concrete member which comprises: forming a layer of solidified fusible material from molten fusible material upOn the surface of a pool of liquid of greater density than said fusible material and at a temperature below the melting point of the fusible material to provide a mold bottom element in a mold structure having mold side elements; casting a concrete member in said mold structure by introducing a concrete mix into said mold structure and into contact with said mold bottom element and allowing said concrete mix to set; and heating said fusible material to a temperature above the the melting point of said fusible material to melt said fusible material and separating the melted fusible material from said concrete member.
 13. The process of claim 12 in which the concrete mix is introduced into said mold structure and allowed to set while said solidified fusible material is at least partly supported by said liquid.
 14. The process of claim 13 in which said solidified fusible material is also partly supported by a supporting structure having spaced elements for providing contact between the lower surface of said mold bottom element and said liquid.
 15. The process of claim 12 which includes positioning said mold side elements to have their lower edges embedded in said layer of fusible material.
 16. The process of claim 12 in which a reinforcing structure having a spaced upper and lower horizontally extending reinforcing elements and vertically extending reinforcing elements connected between horizontally extending reinforcing elements is positioned with said lower horizontally extending reinforcing elements immersed in said concrete mix and with said upper horizontally extending reinforcing elements supported above and spaced from said mold structure and within a similar upper mold structure; and additional liquid at a temperature below the melting point of said fusible material is introduced into said tank to raise the liquid to a level below and adjacent said upper mold structure; and forming an upper layer of solidified fusible material upon the surface of said additional liquid to provide a mold bottom element for said upper mold; casting a second concrete member in said second mold and allowing it to set; and thereafter employing said heated liquid to melt said fusible material.
 17. The process of claim 12 in which the fusible material in molten form is distributed upon the surface of said pool while the liquid of said pool is at a temperature causing a film of solid fusible material to form on said liquid; additional molten fusible material is thereafter distributed upon said thin layer to form a layer of molten fusible material superimposed on said film; and additional liquid is circulated below said layer to remove heat from said fusible material to solidify said fusible material into a solid layer.
 18. The process of claim 12 in which said solidified fusible material is a wax and is partly supported by a reticulated supporting structure.
 19. The process of claim 18 in which a layer of said fusible material is cooled to solid form while in contact with said reticulated supporting structure and while said reticulated supporting structure is at least partly embedded in said fusible material with a portion of said layer extending above said reticulated supporting structure.
 20. The process of claim 18 in which the melted fusible material is solidified when said portion of said layer is sufficiently thin to provide a pattern of ridges on the upper surface of said layer similar to the solid elements of said reticulated supporting structure to thereby provide a decorative pattern on a concrete member cast in contact with the said upper surface of said layer.
 21. The process of claim 19 in which sufficient melted fusible material is added to cause said supper surface of said layer to have a substantially smooth upper surface.
 22. The process of claim 19 in which a decorative insert is supported on said reticulated supporting structure and said layer of fusible material and is partly submerged in said layer of fusible maTerial. 